Sideboard



FIG. 1 is a perspective view of a sideboard showing our new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a right side perspective view thereof, the left side being a mirror image of the right side; and,

FIG. 4 is a top plan view thereof.

The surfaces or portions of the article not shown in the Figures or described in the specification form no part of the claimed design. 

The ornamental design for a sideboard, as shown and described. 